2017

This review provides a commentary on the rodent and human literature investigating the effects of intermittent energy restriction and time-restricted feeding on glucose and lipid metabolism. There is growing evidence demonstrating the beneﬁts of intermittent energy restriction on glucose and lipid homeostasis in the short-to-medium term. Whilst the metabolic beneﬁts of time-restricted feeding appear quite profound in rodents, ﬁndings from the few human studies have been mixed. The frequently repeated prolonged fasting intervals may favour preferential reduction of ectopic fat, beneﬁcially modulate aspects of adipose tissue physiology/morphology, and may also impinge on circadian-clock regulation.

This acute, three-way cross-over study aimed to characterise the early metabolic response to varying degrees of energy restriction. 10 healthy, overweight/obese participants completed three 1-day dietary interventions in a randomised order with a 1-week washout period: isoenergetic intake, partial (75%) energy restriction using LighterLife Foodpacks and total (100%) energy restriction. Relative to the isoenergetic control, postprandial glucose responses were increased following total energy and to a lesser extent after partial energy restriction; there was also a delay in the glucose time to peak after total energy restriction only. Both total and partial energy-restriction interventions produced comparable reductions in postprandial triacylglyceride responses and 3-day energy intake deficits of approximately 30%. The data demonstrate the ability of substantial energy restriction to acutely alter postprandial glucose-lipid metabolism, with partial energy restriction producing the more favourable overall response, as well as incomplete energy-intake compensation amongst overweight/obese participants.2016 Antoni TER and PERRead more.

Little is known about the acute effects of total and partial energy restriction on postprandial substrate metabolism within overweight/obese populations. In this three-way cross-over dietary investigation, 10 healthy, overweight/obese participants completed three 1-day dietary interventions in a randomised order with a 1-week washout period: isoenergetic intake, partial (75%) energy restriction using LighterLife Foodpacks and total (100%) energy restriction. One day of substantial (75-100 %) energy restriction produced acute improvements in postprandial triacylglycerol. By allowing some food intake, partial energy restriction was able to mitigate the increase in postprandial glycaemia found with total fasting whilst producing a comparable three-day energy deficit. These findings highlight the potential utility of intermittent energy restriction as a treatment strategy for hyperlipidaemia.2016 Antoni substrate metabolismRead more.

The comparative effects of continuous (CER) versus intermittent (IER) energy restriction on anthropometry and diet quality (DQ) in a selected group of National Health Service (NHS) weight-loss patients.

Continuous energy restriction (CER) is the first-line advice within the NHS for patients wishing to lose weight, although alternatives such as intermittent energy restriction (IER) have gained increasing attention; IER is now of considerable interest both in terms of energy balance and its potentially beneficial effects on cardiometabolic health. This study aimed to compare the effectiveness of IER v CER on a range of outcome measures, including weight loss and biomarkers of CVD risk, and is the first dietary-intervention trial comparing CER and IER in an NHS tier-three obesity setting (Rotherham Institute of Obesity, RIO). During the 26-week intervention, 15 CER participants were instructed to follow a health diet with a 500 kcal/day deficit, while 23 IER participants were instructed to follow a healthy diet 5 days/week and to ‘fast’ on 2 days a week using a formula-based, 600 kcal very-low-calorie diet (LighterLife Fastpacks). While both groups lost weight during the 26-week intervention, the IER group experienced a greater reduction in total body weight. This trial reflects the ‘real-life’ implementation of weight-management programmes and is thus clinically meaningful.

Continuous energy restriction as a method of weight reduction has been associated with poor long-term compliance. Alternative approaches to weight loss, such as intermittent energy restriction, have therefore attracted increasing attention. Previous research has been limited to a small number of studies of short duration. This was the first intervention trial comparing continuous energy restriction versus intermittent energy restriction within an NHS tier-three obesity setting (Rotherham Institute for Obesity, RIO). In this preliminary analysis, data from the first 38 obese participants to complete the 26-week intervention were included. Both the continuous and intermittent energy restriction groups lost weight; however, contrary to previous research, the intermittent energy restriction group experienced a greater reduction in total body weight and fat mass. As this trial directly reflected the ‘real-life’ implementation of these weight-management programmes, it is thus clinically meaningful.

The intermittent energy restriction approach to weight loss involves short spells of severe (75-100%) energy restriction alternated with ad libitum intake. Lean subjects are unable, via energy intake, to fully compensate for acute 36-hour periods of severe energy restriction, but investigations in overweight/obese individuals are lacking. This pilot study (a randomised 3-way cross-over, minimum 1 week washout) compared the effects of 1 day of total (100%) and partial (75%) energy restriction on subsequent energy compensation and macronutrient selection in 10 overweight/obese subjects, and found they were unable to fully compensate for energy deficits following severe energy restriction. This is the first cross-over study to show that partial energy restriction can produce similar energy deficits to total energy restriction in the short term, suggesting individuals need not fast completely.

2014

‘Intermittent energy restriction (IER) has become the subject of considerable scientific interest as a potential dietary approach for weight loss and improving cardiometabolic health. This approach involves intermittent periods of total or partial energy restriction (ER) alternated with non-restricted intake, and has been studied in rodent and human populations. This review aims to provide an overview of the IER literature to date, with a specific focus on its effects on cardiometabolic health indices in rodents and humans. Current evidence from studies in rodents and humans suggests that IER is capable of promoting weight-loss and/or favourably influencing an array of cardiometabolic health indices, with equal or greater efficacy than conventional continuous ER approaches… Ultimately, whilst much remains to be learned about IER, including its mechanisms of action and long-term efficacy, the positive findings to date serve to highlight promising avenues for future research.’

An intermittent-energy restriction approach to weight loss is easier for some individuals to follow as it involves short spells of severe energy restriction alternated with days of habitual energy intake. We aim to compare the feasibility and efficacy of intermittent-energy restriction with continuous-energy restriction on a range of outcomes in a selected cohort of NHS Rotherham Institute of Obesity (RIO) weight-loss patients. A stratified, parallel, 6-month intervention trial with two groups, each containing 100 RIO patient volunteers, will be run. The intermittent-energy restriction leg of this study will be delivered in the form of the LighterLife Fast plan which advocates 5 days unrestricted healthy eating and 2 days fasting (where 4 LighterLife Foodpacks provide circa 600 kcal/day). This will be compared with the continuous-energy restriction leg of the study whereby patients will be instructed to consume a healthy diet with a daily deficit of approximately 500 kcal. Outcomes measured will include weight loss, changes in waist circumference and other cardiometabolic disease-risk markers.

Intermittent energy restriction is of considerable interest with regards to its role in weight management. However, there is also evidence to suggest that energy restriction itself can confer beneficial metabolic changes, independent to those of weight loss. Whilst the impact of following an intermittent-energy restriction eating plan on insulin resistance has been studied in overweight and obese women, neither the acute nor chronic effects of intermittent-energy restriction on glucose tolerance and B-cell function in the non-obese population are well understood. We aim to compare the effects of intermittent-energy restriction on a postprandial glucose tolerance, insulin secretion and lipid profiles in healthy, non-obese volunteers.

This review aims to provide an overview of the intermittent-energy restriction literature to date, with a specific focus on its effects on cardiometabolic health indices in rodents and humans. Current evidence suggests that intermittent-energy restriction is capable of promoting weight-loss and/or favourably influencing an array of cardiometabolic health indices, with equal or greater efficacy than conventional continuous-energy restriction approaches. Whilst much remains to be learned about intermittent-energy restriction, including its mechanisms of action and long-term efficacy, the positive findings to date serve to highlight promising avenues for future research.

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